The rapid development of integration modules has gained the increasing attention in a multi-chip-module package. Because a multi-chip-module includes multiple chips, the energy consumption is usually high in a single package, which leads to the need of integrating a heat slug in the package for heat dissipation to avoid the over-heating problem caused by the high energy consumption. Currently, the RF front-end module (RF FEM) has successfully integrated the balance/unbalance (balun) transformer, the power amplifier, the duplexer, the switch, the band-pass filter and the low noise amplifier (LNA) into a single package. Although the RF FEM is highly integrated, the antenna, being the front-most element, is still placed in a different module. As the demands of the integration increases, it is inevitable to integrate the antenna into the same RF FEM to achieve an even higher integration.
FIGS. 1A–1D show a packaging process with a heat slug. FIG. 1A is a side view of a multi-chip-module after the steps of die attach and wire bond. Dies 120 are attached and bonded on a substrate 120 via the gold wire 122. FIG. 1B is a side view of a multi-chip-module after the steps of heat slug attach and compound molding. After attaching a heat slug 114 on the substrate 130, the packaged module is filled with the epoxy 160 via a dispenser. The heat slug 114 usually has a round shape and a plurality of support elements 115, as shown in FIG. 1C. The heat slug 114 is usually made by cutting or molding a metal sheet. After folding the metal sheet along the bend line 116 into a n-like shape, the heat slug 114 is placed on the substrate 130 to form a multi-chip-module. FIG. 1D is a side view of the multi-chip-module after a plurality of metal solder balls 150 are placed into the multi-chip-module.
U.S. Pat. No. 6,686,649 disclosed an antenna and a shield fabricated respectively on both sides of a dielectric cap, and the aforementioned structure is placed on top of the chip in the packaging process to achieve the high integration. However, the design is complicated and the fabrication cost is high. In addition, the placement of the dielectric cap is not suitable for the current IC packaging methods.
U.S. Patent publication 2004/0,032,371 disclosed an apparatus of antenna with an electromagnetic shield used in the mobile products. The metal antenna and electromagnetic shield are formed respectively on the top and the bottom sides of a dielectric body. The dielectric body can be fixed on a printed circuit board (PCB). This method incurs a higher fabrication cost for the dielectric body. In addition, the antenna and the electromagnetic shield require the deposit and plate steps in the fabricating process as well as the addition of a metal pattern, both increase the fabrication cost.
European Patent 1,126,522 disclosed an antenna and a plurality of ground surfaces in a multi-layered structure formed respectively on both sides of a dielectric body. The elements in this structure are vertically connected. For example, the antenna feed and ground lines are performed using via holes. In other words, the drilling and the metal filling steps must be included in the fabricating process. As this packaging method is a non-standard IC packaging process, the cost is high.
Because of the aforementioned problems, it is imperative to provide an antenna having a simple structure and a low fabrication cost that can be integrated into a packaging to reduce the overall cost.